non-Gaussian Distribution (non-gaussian + distribution)

Distribution by Scientific Domains

Selected Abstracts

The non-Gaussian nature of bibliometric and scientometric distributions: A new approach to interpretation

Ludmila E. Ivancheva
An attempt has been made to give an answer to the question: Why do most bibliometric and scientometric laws reveal characters of Non-Gaussian distributions, i.e., have unduly long "tails"? We tried to apply the approach of the so-called "Universal Law," discovered by G. Stankov (1997, 1998). The basic principle we have used here is that of the reciprocity of energy and space. A new "wave concept" of scientific information has been propounded, in which terms the well-known bibliometric and scientometric distributions find a rather satisfactory explanation. One of the made corollaries is that , = 1 is the most reasonable value for the family of Zipf laws, applied to information or social phenomena. [source]

Finnegan neonatal abstinence scoring system: normal values for first 3 days and weeks 5,6 in non-addicted infants

ADDICTION, Issue 3 2010
Urs Zimmermann-Baer
ABSTRACT Objective The neonatal abstinence scoring system proposed by Finnegan is used widely in neonatal units to initiate and to guide therapy in babies of opiate-dependent mothers. The purpose of this study was to assess the variability of the scores in newborns and infants not exposed to opiates during the first 3 days of life and during 3 consecutive days in weeks 5 or 6. Patients and methods Healthy neonates born after 34 completed weeks of gestation, whose parents denied opiate consumption and gave informed consent, were included in this observational study. Infants with signs or symptoms of disease or with feeding problems were excluded. A modified scoring system was used every 8 hours during 72 hours by trained nurses; 102 neonates were observed for the first 3 days of life and 26 neonates in weeks 5,6. A meconium sample and a urine sample at weeks 5,6 were stored from all infants to be analysed for drugs when the baby scored high. Given a non-Gaussian distribution the scores were represented as percentiles. Results During the first 3 days of life median scores remained stable at 2 but the variability increased, with the 95th percentile rising from 5.5 on day 1 to 7 on day 2. At weeks 5,6 median values were higher during daytime (50th percentile = 5, 95th percentile = 8) than night-time (50th percentile = 2, 95th percentile = 6, P = 0.02). Conclusion Scores increase from days 1,3 to weeks 5,6 and show day,night cycles with 5,6 weeks. Values above 8 can be considered pathological. This data may help to raise suspicion of narcotic withdrawal and to guide therapy. [source]

Approximate Formula for the Contact between Truncated Surfaces and Frictional Characteristics of a Journal Bearing in Mixed Lubrication

M. Nonogaki
Abstract This paper presents an approximate formula for the contact of a non-Gaussian distribution of truncated surfaces, which is useful for mixed lubrication theory, and gives a method for the determination of the truncation parameters in this formula from a measured roughness profile. Using this approximate formula for a contact, the approximate formula for the friction coefficient of a journal bearing in mixed lubrication, which was previously proposed by the authors, is modified for truncated surfaces, and the frictional characteristics are demonstrated for various parameters of truncated roughness using the modified formula. [source]

A General Empirical Law of Public Budgets: A Comparative Analysis

Bryan D. Jones
We examine regularities and differences in public budgeting in comparative perspective. Budgets quantify collective political decisions made in response to incoming information, the preferences of decision makers, and the institutions that structure how decisions are made. We first establish that the distribution of budget changes in many Western democracies follows a non-Gaussian distribution, the power function. This implies that budgets are highly incremental, yet occasionally are punctuated by large changes. This pattern holds regardless of the type of political system,parliamentary or presidential,and for level of government. By studying the power function's exponents we find systematic differences for budgetary increases versus decreases (the former are more punctuated) in most systems, and for levels of government (local governments are less punctuated). Finally, we show that differences among countries in the coefficients of the general budget law correspond to differences in formal institutional structures. While the general form of the law is probably dictated by the fundamental operations of human and organizational information processing, differences in the magnitudes of the law's basic parameters are country- and institution-specific. [source]

ORIGINAL ARTICLE: How Should Data on Murine Spontaneous Abortion Rates be Expressed and Analyzed?

David A. Clark
Problem, Spontaneous abortions in the CBA DBA/2 model are normally reported as number of resorptions/total number of implantations (R/T), pooling data from individual mice. The significance of differences between groups has been determined using non-parametric statistics (e.g. chi-square or Fisher's Exact test) based on a priori predictions. Recently, it has been argued that medians with box plots should replace the accepted standard, but this deprives readers of data needed to verify P -values, and leads to inferences incompatible with biological and statistical reality. Method of study, Raw data on 173 individual CBA DBA/2 matings were analyzed by median and mean, along with R/T data from 18 independent experiments containing 5,10 mice per group. Raw data from 19 CBA BALB/c matings were similarly analyzed. Results, Individual CBA DBA/2 mouse resorption rates showed a non-Gaussian distribution, but the mean and median differed by <0.5%. Resorption data from 6 and 12 independent pools of mice were normally distributed. Only the mean enabled a between-group P -value calculation. CBA BALB/c matings gave a median of 0 and mean of 5.1%; the data were not normally distributed, but that was because of a bimodal distribution. One group of mice had 0 abortions, and the second a mean of 13.9% abortions, and the data from the latter group were normally distributed. Conclusion, Although it is possible to compare individual mice, and even individual implantation sites, in resorption (abortion) studies, as the relevant question is the significance of differences between treatment groups of mice, and reproducibility, the established classical method of reporting R/T should continue to be provided. In CBA BALB/c matings, where abortion rates are low, using the median is misleading and may obscure the existence of two distinct populations. [source]

Blind separation of delayed instantaneous mixtures: a cross-correlation based approach

Muhammad Z. Ikram
Abstract A cross-correlation based method is proposed for blind separation of statistically uncorrelated i.i.d. signals. In contrast to much of the existing work in the area, the proposed method allows the separation of more sources than sensors and the sensors are not restricted to have non-Gaussian distributions. The mixed signals are modelled as a sum of attenuated and delayed source signals. As compared to the delayless mixture model commonly employed in the literature, incorporating delays in the model may offer better fit to practical applications, such as source separation in an anechoic environment. We estimate the delay and attenuation parameters from the peak locations and strengths of the cross-correlation function, respectively. Using these parameters, we then discuss the use of four methods for the recovery of source signals. These methods are compared and their usage is proposed under different operating conditions. Copyright 2004 John Wiley & Sons, Ltd. [source]

Synchronization patterns in spaghetti-like nanoclusters

Acep Purqon
Abstract Spaghetti-like nanoclusters concern disordered shapes and irregular shape fluctuations in few correlated biological lipids. We evaluate the shape fluctuations by introducing Symmetry- S as a physical parameter for measuring symmetry degrees and detecting shape transitions. From numerical simulation of few correlated lipids of POPC and POPE at 300 K and 340 K by using molecular dynamics, we investigate the symmetry dynamics for each individual cluster by analyzing both spatiotemporal and frequency. From spatiotemporal analysis, we find several jump motions in S -dynamics and non-Gaussian distributions in S -distribution. Interestingly, the jump motions likely contribute on the existence of transitions in the non-Gaussian distributions. Additionally, even number of lipids show more symmetric than the odd number of lipids and the symmetry distributions shift at higher temperature, while, from three dimension of actual position of symmetry dynamics, they are not easy to configure high symmetry as well as showing certain patterns. From power spectra density analysis, each individual cluster shows nearly random fluctuation. Besides individual clusters, we also investigate mutual clusters. Surprisingly, although individual clusters show fluctuations randomly, mutual clusters show certain direction correlations. Moreover, they show certain patterns in delayed time analysis such as mutual fluctuations periodically occur for same number of lipids. It indicates that an existence of synchronization patterns occur in shape fluctuations of spaghetti-like nanoclusters. 2008 Wiley Periodicals, Inc. Int J Quantum Chem, 2008 [source]